Amlodipine is a well-known calcium channel-blocking agent which is used in the treatment of hypertension and angina. Amlodipine is a dihydropyridine with an asymmetric centre at the 4-position; presently, amlodipine is only approved for administration in the form of the racemate, specifically that of the besylate salt.
The individual enantiomers of amlodipine have been isolated (J Med Chem 29 1696 (1986), Arrowsmith et al) and identified as R(+) and S(−) (J Med Chem 35 3341-3344 (1992), Goldmann et al). The calcium channel-blocking activity of the racemate has been found to reside largely, but not exclusively, in the S(−) enantiomer (J Cardiovasc Pharmacol 12 (Supp 6) S144, J W Rigby et al).
European Patent No. 0754043 describes the surprising ability of the R(+) enantiomer of amlodipine to inhibit PDGF-induced vascular smooth muscle cell migration using an in vitro system which effect may prove to be useful in the treatment of conditions such as atherosclerosis, restenosis after angioplasty and endometriosis.